Baffle type muffler with plural expansion chambers



L.. R. BESTER 2,485,555

BAFFLE TYPE MUFFLER WITH PLURAL EXPANSION CHAMBER Oct. 25, 1949.

L. IR. BESTER BAFFLE TYPE MUFFLER WITH PLURAL EXPANSION CHAMBER 4 Sheets-Sheet 2 Filed Dec. 15, 1944 BAFFLE TYPE MUFFLER WITH PLURAL EXPANSION CHAMBER L. R. BESTER 4 Snees-Sheet 3 Filed Dec.

L. R. BESTER Oct. 2.5, 1949.

BAFFLE TYPEI MUFFLER WITH PLURAL EXPANSION CHAMBER 4 Sheets-Sheet 4 Filed Dec. 15, 1944 ear-mrd E. Besfer Patented Oct. 25, 1949 vBAFFLE TYPE MUFFLE-R WITH .PLURAL EXPANSION CHAMBERS "Leonard R.'Bester, New York, N. Y.

Application December 15, 1944, Serial @10.568.370

l(Granted under the act of March 3, 18'83, I'as amended April 30, 1928; .3710 (3.. G. 757?) Claims.

The present invention relates to muffler-5, particularly those adapted #for `-.use with internal combustion feng'ines. These lmufers may be of the Wet or fdry :ty-pe. The several 'forms herein disclosed .are based 'von the nozzle suction principle, and are designed .so 'as'to absorb the pulsations :ci the lexhaust @gases by successive expansions in chambers alongside .the main gas passagegcvhichk yis continuous throughout the muffler in one direction. The smain- .passage `for the gases, although interrupted by rbaies, is never lturned back -inffreverse direction but :has ra component towardthe mu-filler `:outlet .at all peints :along its course. The :resul-tisapgreat attenuation ofthe noise )level without any appreciable rise in back pressure, as compared to fmuiliers now in common use.

One of thelobjects :of this .invention is -to construct a muilier oi the 'wet or drzy Wpc hav-ing a :directiiow which, .although divertediby `a series of haines, at `no 'point reverses itself, but has at all points some lcomponent inthe direction toward the ,mufller outlet.

yAnother :object :is to construct Aa .muffler :of the wet or .dry type -having ta series 'of :conical 'nozzles converging Atoward the -foutlet'of the mufller and being annular-ly spaced from the "wall of the muler chamber. Y

Another object is the construction of .a muiler ofthe wet-for dry typehaving-.one'or .more conical shaped nozzles axial-lyarranged therein `near the inlet to the 'muillernand followed -by `a series of conical baffles, the-alternate v.baffles -of this series having openings around the periphery Yand through the center thereof, soy as -rto* cause the gases flowing therethrough-cto vbe alternately diverted outwardly around the periphery Aof one baille vand inwardly through the central opening in the next, the baiiles with the peripheral openings having `theirlapex turned.v upstream whereas the baffles having .the central iopening are turned so as to -.converge downstream.

Another object is to `construct .a vmuffler of the wet or dry type having a cylindrical Icasi-ng with one or more :conical shaped nozzles arranged near the inlet, and a series of Vconical battles having central openings, the #alternate baffles being turned lto couver-geinlopposite'directions with respect to the flow of gases therethrough.

Another object is to` constructsJ muffler of the wet for dry type having a casing of lgeneral-1y circula-r cross-.section but having a smaller diameter at its inlet end,.andaseries ci conical-shaped nozzles axially .arranged therein, and ya conical baffle at the enlargedaend, :annularly .spaced yirouo thercasin'g and-having its apex turned upstream, the outlet of thefmufer 'being formed .by :aser'ies of .conical-shaped nozzles diverging outwardly to `form annular outlets therebetween, the last conical nozzle being (obstructed by a conical plug to Aform the last annular opening in the series. Further and more .specic Aobjects of vthis invention `will become apparent zas the description proceeds, having :reference to the accompanying drawings, wherein:

Fig. 1 isa sectional View 'of one form of the muier oT this invention, illustrating `a combination jof V.nozzles Yand .baffles in vaccordance withl thel :principle used herein,

Eig. '2 is another form lof :nuiiler having -a similar arrangement `of :alternate conical v`cailles, in which the conical walls make a smaller angle with the axis :of the muler,

Figs. 23 Ito '.6 .illustrate another 'construction wherein only one conical nozzle is used near the inlet end,-and the series of 'alternately arranged conical ballies make an intermediate 4angle with the `'axis of Kthe mufller.,

Fig. '7 is a diagrammatical illustration of still another form-of mulers having a continuous passagestra-ight :through the `middle :of the mufiler., the Ialternately larranged fconical baffles all having central :openings therein,

,Fig 8 represents diagrammatically a form of muiiiers adaptable for 'use Lon aircraft engines where the :exhaust is exposed to the ai-r stream to obtain vthe :benefit of Ithe suction eiect ythere- 0f,

Fig. `9 .is a .form similar to "that :of Fig. 8 `but having 'a :slightly diner-.ent arrangement vof thel bailleiand 3being provided with inlets for air `near the inlet for the exhaust gases,.fand

Figs. l0 .and 1l Aillustrate -other forms oi.' wet type muilers.

The :purpose of the conical nozzles yused in the muiiiersofth'e -present invention is to recirculate and gradually expand the explosion impulses by successive expansions of the gases, and vto inject them back into the direct flow, thereby causing attenuation :of the excess pressure impulses by absorbing expansions and by .reductions in temperature, so that the excess pressure pulsations in the expansion .space lafter lthe last nozzle and before `the outlet :is reached, .isalmost nil. The gases simply flow through Ithe outlet *evenly without `any explosion pulses -and .are smoothly pushed out ,by reason .of thecontinuous `accumula-- tion of `.gases behind them. The use of the alternately larranged conical :baffles further attenuates not only lthe pressure pulses but falso the `noise so as to reduce it to a very low level by the time the gases reach the outlet. The inlet end of the mulller may be provided, as shown in some of the forms illustrated, with an arrangement to introduce cooling water where wet muiiler types are desired, or to inject air in some of the forms for cooling purposes.

Referring more specifically to the several figures in the drawings, Fig. 1 shows a muffler having a cylindrical casing I with an inlet 2 at one end and an outlet 3 at the other. A water inlet 4 is also provided near the gas inlet 2. A pair of conical shaped nozzles 5 and 6 are suspended in series near the inlet and are annularly spaced from the cylindrical casing I. followed by a series of conical bailies 'I to I3 for diverting the ow of gases, rst outwardly through a peripheral opening I4 and then inwardly through a central opening I5, the openings having gradually increasing area all the way r through the muiller from the inlet to the outlet end. In putting the muiller together, it may be rst made in sections I6 to I9, each section I'I, I8 and I9 having :a pair of the bailles 8 9, III-I I, or I2-I3, mounted therein, and the sections joined end to end at 26, 2 I, etc., by welding process. One or more drain outlets 22, 23 may be provided in the bottom of these sections for draining any excess of water accumulated therein.

Fig. 2 illustrates a similar arrangement of ballles, the conical walls 24 to 28 of which make a much smaller angle with the muffler axis. This mufller does not have any conical nozzles at the inlet end oi the casing. In Figs. 3 to 6, a muffler having a similar arrangement of baflies 39 to 35 is shown but, only one conical nozzle 36 is used at the inlet end and the sections are put together 38, 39 etc., by matching shoulders, and are held together by through bolts 40 extending between the end plates 4I and 42.

in this form is shown connected directly into the gas inlet 44. The baffles and nozzle are held in place by brackets 4'5, 46 mounted in the cylindrical casing sections.

Fig. 7 diagrammatically illustrates another form of mufllers having series of alternately arranged conical baffles 41 to 54, all of which have central openings for a direct axial ow of the gases through the entire muilier, and a pair of nozzles 55, 56 mounted near the inlet end of the casing, and the openings gradually increasing in size from the inlet to the outlet end.

Thus in this form, as well as in all other forms of inuiilers shown herein, a series of expansion chambers is provided along the path of flow for the exhaust impulses to spread into, with annular return passages in the nozzle section for producing a suction effect by the flow of the impulses through the nozzles to draw back some of the expanded gases into the main flow. The expanik sion chambers are produced in various waysin the several forms of the invention. For example, in Fig. 1, the various bailles 1 through I3 are relatively flat and have sides which make an angle of not less than substantially forty-five degrees with the axis of the muiiler to thereby produce considerable turbulence of the gases and some slowing down thereof. Each of the bales is spaced from the adjacent baffles to produce chambers therebetween in which the pulses of gas can sequentially expand, be subjected to turbulence, and subsequently be scavenged therefrom. Thus, the baille I defiects each pulse of gas to cause it to pass through the annular gap I4 between baille 1 and casing I and enter the chamber be- These nozzles are The water inlet l tween baille I and baille 8 where the gas expands with considerable turbulence. The rush of gas through the opening I5 has a tendency to carry with it the gas in the chamber between bailles I and 8 so as to scavenge this chamber before the next pulse of gas arrives. The gas issuing from opening I5 enters the chamber between baiiles 8 and 9 wherein expansion, turbulence and scavenging is repeated. Turbulence has the effect of retarding the gases by slowing them down without creating a back pressure thereby reducing the noise level of the impulses, a series of bailles being effective to smooth the impulses into a uniform expulsion of gas from the outlet 3 o! the muliler.

In Fig. '7, the baffles 41 through 54 are reversed in operation from those of Fig. 1 but because of the spacing between them, the chambers for permitting sequential expansion, turbulence and scavenging are present and operate in the manner disclosed hereinabove.

The suction elect in the nozzles is obtained when the gases emanating from the nozzles, such as nozzle 56 in Fig. 7, are drawn backward as shown by the arrows as a result of the injector effect produced by the inlet pipe and the nozzle thereby permitting expansion and turbulence of the gases in the space between the nozzles and the muffler casing I. This has a great attenuating effect on the explosion impulses, and the reexpansion in the several expansion chambers along the route further attenuates not only the pressure pulses but also the noise level, so that by the time the gases reach the outlet, a smooth even flow at a comparatively low pressure is obtained with a very low noise level. A series of air inlets '51, 58 may be used, passing through the inlet plate 59 of the muflier, as shown in this figure, for supplying cooling air. In this case, a conical baille 56 may be provided to block ofi.' the annular space around the nozzle 56 and direct the gases inwardly into the inlet of nozzle 56.

Fig. 8 diagrammatically illustrates a novel form of mufllers which may be used on aircraft engines, where it is exposed to the air stream, so as to obtain the benefit of the suction effect of the air stream 60 to aid in reducing the back pressure caused by the exhaust gases in the muffler on the engine. The muffler casing 6I in this form is gradually enlarged toward the outlet end and has a series of conical nozzles 62, 63, 64, near the inlet followed by a conical baille 66 converging upstream, annularly spaced from the muliier casing and having a central opening 6'I forming the inlet to a conical nozzle 68, and followed by a further series of conical nozzles 69, 10. The outlet II of this muier is formed by a series of diverging conical nozzles 'I2 to I5 held together by brackets (not shown), so as to form annular opening 'I6 to 80 between the successive nozzles, the last nozzle being balled by a conical plug 8| forming therewith the last annular opening and having a conical end 82 for streamlining effect. Thus, in this form, a continuous axial passage is formed for the main flow, there being some reversal of ow only in the expansion chambers by a part of the gases, which are sucked back into the main flow by the nozzle effect of the iiow of impulses through the nozzles.

In Fig. 9 another form of mullle, particularly adapted for aircraft use, is shown, having a similar shape and arrangement of the nozzles 83 to 86, but being supplied with a perforated conical baffle 81 near the outlet 88, with its apex 90 turned upstream and the perforations 89 directed Inmdiyiimvardithesapexiufthe cone: perfm'a'it'ions Jpiramide for .::a;suctinm1efiect produced by: the from of Sigascsiaromid the 'outside :ci "the cone, drawing someiofrthe :gases from yinside the mimey outwardly ',ithroixglr these Vperforations into .iiiiemain` llhese snuiilersimayalso be provided with air inlets 9|, 92, as shown, :for supplying'coolina v"if desired. In this case also a conical baffle 86 may be used to block off the annular passagearound vthe ba'iile 85. The muffier outlet .isformed similarly tothat shownin Fig. B, lby a series of diverging nozzles-.'93 to 9B and the plug 91.

In Figs. yililwanti 11i, la `wet type lotmufer is shown, :diagrammatically .illustrating fur-.ther modifications in the-.arrangementof nozzles, baffiestand shape of muillers. The form in Fig.. 1-0 has aaserliesof nozzles B8 to .1.0.4 increasingl in from the inlet end toward 4the outlet, and a conicalbailie 102 annularly spaced .from the mufercas'ing M13 with its apex directed upstream, vanda.water drain IM at the lowest point in the nmiernasing. Fig, 11 shows .a mufiier .similar 'inshape but using only three 4conical nozzles .105,

i106, 1307, lat the inlet end, and yhaving a similar conical baffle |08 near the outlet except that itis provided with a central opening |09 forming .an-.inlet vto a sleeve H0, and is followed by an vadditional conical nozzle 4i'll immediately in front of the muffler outlet f'i-I'Z.l

A .se-ries of tests have been made on -muiilers of this -construction, Frcormaa-risons being Vmade with somestandard constructions, and .have indicated a.marked improvement .in reduction of noise level and back pressure as compared with the standard constructions. Obviously the design may be Varied to suit the requirements of the particular installation by regulating the size of openings and arrangements and type of baffles in accordance with the desired results, possibly 4.'.

sacrificing some reduction of back pressure to obtain a better attenuation of noise level or vice versa, as may be desired, as is well known, but in any case the next results should show a marked improvement over existing constructions. Thus in the wet type muffler, the dispersion of a controlled amount of water into the muler may determine the desired reduction in noise level but will also have an opposite effect on the reduction of back pressure at the engine. In the dry type of muffler, the form, arrangement, and size of bailles and nozzles will also have an effect on both noise level and back pressure but it has been found that the arrangements, in general, covered by this disclosure, wherein one or more conical nozzles are used near the inlet end of the muffler combined with one or more conical baiiles provide an unusually good arrangement for reducing both noise level and back pressure in any one particular installation as compared :u

with other constructions of mufllers.

Further advantage of the present constructions of bailies in the muffler is that they prevent the harmful back flow of burned gases back into the engine cylinders, as is the tendency in some internal combustion engines under some conditions of low frequency pulses. This is because the bailles present effective obstructions to a reverse ow of gases by reflecting them in the opposite direction, if there should be any back flow started due to an extended low pressure period between impulses at the engine.

Although the drawings illustrate mulers adapted particularly for use on the exhaust of internal combustion engines, suitable mufilers made according to this invention maymlsoibe designed .for ruse -on air intakes `for carburetor: or in ventilation systems, etc.

One application, to which the present invention lend-seitself more particularly, :is 4:on-the me haust Iof engines for aircraft using large dialne-V ter, low speed pro-pellers which :are nearly @noiseless, such as some of the helicopter types, lighter-than-aircraft, etc. Such craft mayv thus bemade almost absolutely noiseless.

Obviously, many other changes in Aform `anti arrangement of parts in these mufers might abe made besides those illustrated herein without departing from the spirit .and scope of this lnventi'on, :as defined Ain the appended claims.

This invention may be manufactured and used by or for the Government of the United States :ot

America for governmental purposes Without payment fof any royalties thereon or therefor.

What is :claimed is:

1. A muiiler for an internal combustion engine composed vof an inlet section, a plurality of iintermediate sections and an outlet section, each of :said sections being venclosed in a cylindrical tubular portion, the several sections .being consecutively positioned with the vtubular portions forming :a single cylindrical casing; @said inlet section `comprising a tubular portion closed `at oneiend bya plate secured thereto, an inlet pipe vfor said exhaust gases extending through said plate into said vinlet section, a plurality of truncated J'conical shells vconsecutively arranged 'coaxially with said inlet pipe to :form a suction channel, one .of said .shells being disposed with i-ts .larger Itend adjacent'th'e end oisaid iinlet'pipc, and successive .shells being Adisposed with "their larger ends adjacent the smaller end of the preceding shell, the said tubular portion extending beyond the suction channel thus formed, whereby the exhaust gases passing through the shells cause a circulation of the exhaust gases within said inlet section; each of said plurality of intermediate sections comprising, a tubular portion open at its inlet end and its outlet end, a

f first baffle composed of a conical shell of apex angle of substantially more than 90 and a maximum diameter substantially smaller than the diameter of the cylindrical portion, said ilrst baffle being coaxially positioned within said portion with its convex surface toward the inlet end thereof and its apex spaced from the said inlet end, and a second baille composed of a truncated section of a cone having an apex angle of substantially more than 90, said baille having an outside diameter substantially equal to the diameter to said tubular portion, said second baille being coaxially positioned within said tubular portion with its convex surface toward the outlet end thereof, said second baffle beingv spaced from said first bafiie and said outlet end of said tubular portion whereby the exhaust gases passing through said intermediate section cause turbulence within the space between the first and second baffle and on the outlet side of said second bafile; said outlet section comprising a cylindrical portion closed at one end by a plate secured thereto, an outlet baie composed of a conical shell having an apex angle of substantially more than 90 and a maximum' diameter substantially smaller than the diameter of said cylindrical portion, said outlet baffle being coaxially positioned within said cylindrical portion spaced from said open end of said section and from said closed end thereof, and an outlet pipe attached to said plate to conduct said exhaust gases from the muilier.

2. A muier as described in claim 1 in which said inlet section includes an inlet adjacent said inlet pipe for a cooling medium.

3. A muiiler as described in claim 1 in which said inlet section includes an inlet adjacent said inlet pipe for cooling water and the outlet pipe in said outlet section is positioned at the bottom of said outlet section.

4'. In a muier for the exhaust gases of an internal combustion engine, a substantially closed casing having an inlet end, an outlet end, and containing a single chamber, said casing containing a plurality of oppositely disposed conical bales coaxially positioned within said chamber, an inlet pipe extending through the inlet end 3.

of said casing, at least one truncated conical nozzle having a diameter substantially smaller than said casing positioned within said chamber coaxial with and spaced from said inlet pipe and having its larger end adjacent the end 0f said inlet pipe and spaced from the inlet end of said casing, said nozzle and the baille adjacent said nozzle dening an expansion chamber therebetween, whereby the exhaust gases passing through said nozzle cause a low pressure area surrounding said nozzle and cause a recirculation of the gases, said plurality of conical baiiies being coaxially disposed within said casing between the conical nozzle and said outlet end of said casing with adjacent baffle elements spaced from' each other, each pair thereof deiining an expansion chamber therebetween in which the gases are subsequently expanded, subjected to turbulence and scavenged therefrom, an exhaust means in the outlet end of said casing for allowing said gases to leave the casing.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 624,062 Matthews et al May 2, 1899 1,061,272 DeWitt May 13, 1913 1,084,883 Holzwarth Jan. 20, 1914 1,162,064 Hutton Nov. 30, 1915 1,169,030 Hardy Jan. 18, 1916 1,685,701 Blanchard Sept. 25, 1928 1,760,924 Watkins June 3, 1930 1,874,326 Mason Aug. 30, 1932 1,991,014 Compo Feb. 12, 1935 1,990,837 Morgenstern Feb. 12, 1935 2,024,834 Rippe Dec. 17, 1935 2,088,576 Compo Aug. 3, 1937 2,330,534 Wood Sept. 28, 1943 FOREIGN PATENTS Number Country Date 19,777 Great Britain Oct. 4, 1901 128,934 Great Britain June 24, 1919 380,278 France Oct. 3, 1907 

